The present invention relates to an open-end wrench, and more particularly to an open-end wrench structural arrangement which represents an improvement in grasping and turning normal or newly-made bolts and nuts of different sizes and/or specifications as well as worn-out bolts and nuts of different sizes and/or specifications.
An open-end wrench is a handy tool that is intensively used for grasping and turning such fasteners as bolts and nuts. Open-end wrenches of the prior art disclose various structural arrangements that include teeth, raised portions and/or rough grasping faces on the jaws that are used for the desired functions of grasping and turning normal bolts and nuts as well as worn-out bolts and nuts. Examples of prior art open-end wrenches of different structural arrangements are shown in FIGS. 1 to 14. The open-end wrenches shown in FIGS. 1 and 2 are especially designed for grasping and turning hexagon head bolts and nuts of different sizes. Further, the open-end wrenches shown in FIGS. 1 to 4 are especially designed for turning worn-out hexagon head bolts and nuts. These prior art wrench designs are operative for turning head bolts that start to wear slightly, however such open-end wrenches do not positively grasp and turn excessively worn-out bolts and nuts in an acceptable and efficient manner.
It is a general object of the present invention to provide an improved structural arrangement for an open-end wrench which avoids the disadvantages of the prior art wrenches illustrated herein while providing additional structural and operating advantages.
It is another object of the present invention to provide an open-end wrench which represents an improved structural arrangement for grasping and turning such fasteners as hexagon head bolts and hexagon nuts as well as square head bolts and square nuts.
It is another object of the present invention to provide an open-end wrench which represents an improved structural arrangement for grasping and turning normal bolts and nuts of different specifications as well as worn-out bolts and nuts of different specifications. According to the present invention, the open-end wrench comprises a mouth defined between two jaws and a nest portion interconnecting the two jaws, a first convex surface portion being provided on the first jaw driving surface; a first transverse tooth, a second transverse tooth and a second convex surface portion being provided on the second jaw driving surface; wherein the first transverse tooth, the second transverse tooth and the second convex surface portion of the second jaw being arranged at predetermined distances from the first convex surface portion of the first jaw driving surface. Further, the distance between the first transverse tooth and the second transverse tooth is arranged to be {fraction (3/25)} of the distance between the first convex surface portion of the first jaw driving surface and the first transverse tooth. By means of the aforesaid structural shapes and critical dimensions, the open-end wrench of the present invention has improvements in grasping and turning normal bolts and nuts as well as worn-out bolts and nuts.